Telephone system



Jan 6, 1931. T. KoRTHAuER TELEPHONE SYSTEM Filed 001;. 30, 1929 Theodor Ker-H121 uer Fl TTORHEY Patented Jan. 6, 1931 UNITED STATES THEODOR KORTHAUER, or BERLIN-SIEMENSSTADT, GERMANY, nssreivoajnx mam ASSIGNMENTS, TO AMERICAN TELEPHO TION OF NEW YORK NE AND TELEGRAPH oomranmnoonronn- TELEPHONE SYSTEM Applicationv filed October 30, 1929, Serial No. 403,489, and in Germany Apri1 l0, 19 28.

This invention relates to electric telephone systems and has particular applicability to systems in which connections are made auto- 7 matically by means of automatic switching mechanisms.

My invention furthermore specifically relates to telephone stations which may be connected either manually or automatically with at least two exchange stations for calling a; subscriber belonging to either one of such scriber belonging to a local exchange, such as a subscriber living in the same building, or to call asubscriber ofa' distant exchange over a distant oflice. Forthis purpose secondary or extension stations of this kind One of these connection lines serves for making a call to a subscriber belonging to'a local exchange and the other one of the connection lines serves for calling a distant subscriber over a distant exchange. The, calling operation performed by the subscriber over the local exchange, as well as over'the distant exchange, may be carried out by means 7 of the well-known switching organs, such as 30 call selectors or PIG-SBlGCbOI'S, the latter'also being called line switches.

With systems of this kind, as used hitherto, it was necessary to equip each one of the connecting lines associated with a telephone station with at least one relay, serving the purpose of initiating the necessary switching operations for the. establishment of the desired connections. This relay, is, preferably, of the type of the so-called step relays and is provided, for instance, with at least two windings energized successively, whereby successive switching movements are carried out, the first operating step, e. g., initiating the switching operation for performing the desired connection and. the second operating step releasing the switching mechanism when the connection has been completed. It is not necessary, however, for the purpose of my invention, to use such specific step relay, but any other relay, such as a calling relay and a have been provided with two connection lines.

separating relay, may beprovided for obtaining this object just'mentioned. This will be more particularly described .in connection With the circuit diagram illustrated inthe accompanying drawing. 7

With stations of this nature, which may connect and maybe connected over a local exchange, as well as over a distant exchange,

ing subscriber may connect himself with a distant line. By the use of such 'a key or other switching device, it isnecessary to em ploy a. special translating arrangement or a switching device, such as a key, is usually provided, by'the operation of which the callrepeater in the distant line, in order to prevent objectionable and undesiredswitching operations connecting one-of the lines to the ground when a scriberr 7 It is the v j design a circuit system, according to which a f single relay is provided for both the connection lines, which is renderedeft'ective when making a local call and which will be inefi'ective when making a distant call.

A further object of this invention consists of dispensing with a special translating device or repeater to be inserted in the distant line connection. i

These andfurther objects of my invention will become morev apparent as thevfollowing detailed description proceeds, which'is' taken with reference to the accompanying drawing,

which illustrates, by way of example, two

circuit diagrams of a telephone system, in which my invention may be embodied; I Wish it to be'un'derstood, however, that this description in reference to the specific exampleillustrated by the drawing serves the purpose of illustration only ofthe basic and fundamental principleforming the subject matter otmy inventionand that this specific description should not, in any way, have the effect of limiting the invention, short of its broad and most comprehensive scope, asexpressed in the appended claims.

Figure 1 shows a circuit diagram of a telephone system, in which the idea-of my invention isembodied, wherein two difierent call is madeby the sub- 7 cited.

telephone sets are provided for initiating a local or a distant call, respectively.

Figure 2 shows a similar diagram to Figure 1, representing a simplified system, as compared to Figure 1, whereby a single set is provided serving for making either a local or a distant call.

Referring more particularly to Figure 1 of the drawing, a diagram of a'telephone station is shown, which'may connect itself over a distant exchange, aswell as over a local" exchange. In the example illustrated, two

separate sets are shown for communicating ing, let it .be assumed that the subscriber Wishes to be connected over the distant exchange. The operation will then be as follows: 7 v

I To make such a call, the subscriber has to, lift his receiver from the hook switch of his set, which latter is designated bythe character A inthe drawing. Furthermore, hehas to press a key Ta, which is provided at his second set vI-I, tobe used for making a local call. With the lifting'of the receiver .of the set A for making distant calls, the

following electrical circuit isformed for. the

two windings I of the relay T and the relay B, respectively: From ground to closed key Ta, connecting line a3, resting contact 16, winding I of relay T, which has .a high ohmic resistance windingl of the relay R,

to batteryand back to ground. By the establishment ofthis circuit, the relay R becomesenergized. This relay is of the type of differential relays and may beoperated only by pressing the key Ta. When making "a call over the local exchange by the calling subscriber, the differential relay R is not ex This will be more particularly de scribed later on, in connection with the operation for making a local call over the local exchange. With the energization of the relay R, a contact 81" is closed, whereby the following further circuit is established: From ground to battery, to winding I of a further relay C, to resting contact M2, to winding II of the relay C, to working contact .31, back to ground.

By the terms resting contact and wor ing contact, the position of the relay contacts is understood to correspond to the relay been shown, as being'out of the scope of the .line are simultaneously disconnected.

winding in its de-e'nergized condition and its energized condition, respectively.

Through the establishment of the last mentioned circuit and the energization of the relay C, its contact 50 is closed, whereby the further circuit --for the rotary operating magnet M of the call selector AS is closed, which latter is connected with the connection line leading to the distant exchange. The operating current circuit for the operating magnet 'M of the call selector AS is traced as follows: From ground, to battery,

to interrupter U, to operating winding of rotary magnet M, working contact 50, resting contact 68, back to ground. The switch 5 arm of the call selector, in accordance with its well known operation, will thus start to travel over its bank of contacts and plck out the calllng line. is soon as it has found 1t,

the following test circuit is formed: Ground,: 5

to battery, to resistance VVZ', to resting contact 70, to winding of relay S, to resting contact 87), to double working contact 90, to switch-arm cl of the call selector, to working contact lt, across connecting line a3, acrossi'ieo' ciosed key Ta, back to ground. The key Ta has to be pressed down by the calling subscriberuntil a signal is given to" him from the distant exchange. With the establishment of the last mentioned circuit, the relay5'95 S becomes energized, whereby it operates its contacts 65 and 108. By the opening of the contact (is, the current for the rotary operating magnet .liI of the call selector AS is interrupted. By theclosing of the contact' 10s, a current is formed for the relay V,

which is traced asfollows: From ground, to

working contact 105, across winding of the relay V, to battery, back to ground.

A lamp L isconnected in parallel to therelay winding V. This lamp will light up,

whereby the operator of the local exchange is notified that a connecting line to the distant exchange has been occupied. The operator at the distant exchange is notified at the same time of the call and connects herself withthe calling subscriber, who informs the operator which subscriber he wishes to be connected with. The desired connection is then made by the operator in the wellknown manner. Of course, it may also be made automatically, by means of selector or connector mechanisms, but this is not described more fully in the present example, as,

'it is out of the scope of the principle underlying the invention.

By theenergization of the relay V, the contacts to, 7'2), 81 and 11 0 will be operated. By the reversal of the contacts 7 0, 812 and 11?), the connectingline is switched over to the distant exchange and the switching devices (relays) associated with the connecting By the reversal of the contact 411, the circuit 1 the same time,'the callingsubscriber releases the key Ta, when he receives a signal from the exchanged How this signal is given tohim will not be described in more detail, as this is not concerned with the invention itself. Thus, the relay 'R will be 'de-energized, whereas the relay S willhold itself by means of the operating current supplied from the exchange to the subscribers circuit. The call selector AS is blocked as contact 68 is in its working position and accordingly,

- the rotary magnet winding-M de ene'rgized.

After completion of a conversation with the distant exchange, the connection will be dissolved again in the Well-known manner. The relays S and Vare released and the C011- nection line is available for a. new call.

Assuming now a call with a local subrscriber is desired, the operation will then be as follows:

The extension subscriber connected to the local exchange in this case has to lift his receiver from the set H provided for making local calls. Thus theffollowing circuit will beformed r From ground, to battery, to Winding I of the relay R, to winding I of the relay T, to resting contact 1t, over connecting-line a3, through the set for making local calls 1-1, over connecting line'b3, to resting contact 1123, to winding II of the relay T, winding II of I the relay R, winding of the starting relay An, back to-ground. By the closing of this circuit, the relays Tand'An are energized. Relay T is energized'on accountof its two windings I and II being of unequal resistance, or by arranging both windings in such asense as to assist each other. The differentialrelay R is not operated in this case, as both of its windings are flown through-by the current in the same sense. The step relay T, when operated, reversesthe contact 2t. The relay An serves toestablish, a circuit for the rotary magnet of the call selector ASl of the local exchange. This latter operation is not specifically illustrated in the drawing,

as it has nothing to do with the particular feature of the invention; Thevcall selector ASl is put in operation and selects the calling line. As soon as thisisfound, a further winding III of the step relay T is put in circuit. The relay will thus be. operated to advance a further step, whereby the contacts ltiand 11tare opened. By the opening of these contacts, the relays T and R and An. are separated from the subscribers line.

The further operations for completing the connection to a local subscriber will not be described in more detail, as they are notesseutial to theunderstanding of the inventive object. The local subscriber may, of course, be called by another subscriber also and, in

this way, the call may be efl'ected bynieans of a line switch or pre-selector, which is indicated in the drawing by thecha-rac-ters LIV."

The key Ta is pressed down' by the sub} scriber only when 'he-iwislies tomake a dis-;

tent "call, 'wherebythe' difi'erentiali relay is energized and starts the ca'll selector AS, which connectsthe calling subscriber with the distant exchange, whereas the "operating; relay T for the local call selectors is not excited, as only its winding I of high ohmic resistance is inserted in the circuit. VVh'enunaking a call to a local subscribeiythe key Tashould not be pressed downand,*thus,'the' differential relay will not be operated. inethis case,

described. Theirelays-R- and Anarecommonto all connection lines leading to: local subscribers. Instead of the step-relay T one of which isprovided for each subscriber with two connection lines, it is-ialso possible to use a special calling relay and a separating relay, such as is vwell known in? the. art; It is also made possible, with a system as'illustrated, to make a'return call toa local subscriber during a conversationiwith a distant subscriber, without-it being necessary to give up the distant connection. c

' Referring- 130 Figure. 2.,of the drawings, in which similar reference characters refer to similar parts, a single telephone setis pro.- vided for a subscriber, which may :be' used for making acall either over a .local exchange, or over a distant exchange .;:Allvthe operations, in accordance with-this arrangeinent,vare exactly identicaletosthosedescribed in. reference toF gure 1; f If thesubscrlber desires to make a local callgihe has .to lift his receiver from the? hook switch and the currentflow through both, windings of therelay R is such that compensation takes'place and the relay is, accordingly, rendered inoperative. IVhenever the subscriber wishes to make a call over a distant exchange, he has, besides lifting his receiver, to operate the key Ta, whereby only one winding, of the relay It is excited and thus, the: relay-rendered operative. 'Thecurrent in the latter case for the, relay winding willbe from ground, to winding I of: relayR, to windingI of the relay T, resting contact'lt, connecting line a3, key Ta, back toground- 'In'this latter case, the current will not flow overthe subscriber set a1 and the windings II of the 'relaysT and R, but will go directly to ground across the closed key Ta, as thispathtoground offers the least resistance.

While Ihave described my inventionmore or less specifically, with reference the show ing herein, it is obvious that would have'it understood that the invent-ion may be practiced inmany other ways, as becomes evident from the description, without departing from the spirit and scope thereunder, inattaining the object hereinbefore set forth, I

switching device.

Whatlclnimis: 7 Y

Incombination in a telephone system, comprising a telephone station, two connectlines emanating from said station to a local exchange and to a distant exchange, re 7 comprising a telephone subscriber station, a

connec line amociated with said station leading toa first exchange station, a second connecting line over said station leading to asecond exchange station, a switching device associated with both of said connecting lines, said switching device being inoperative when making a call over said second line and means to be operated when initiating a call over said first line for rendering operative said 3. In a telephone system, a first exchange station, a second exchange station, a subseribers station, a line extending from said subscrihers fiat-ion to said first exchange station, a second line extending from said subscribers station to said second exchange station, a switchmg device consisting of a I relay havingat least two windings, and circuit connections between said relay and said lines whereby when a call is being initiated over said second line compensating currents flow through said windings and when a call is being initiated over said first line the flow of compensating currents in said windings is prevented; I

4. In combination in a telephone System, comprising a telephone subscriber station, a connectingline associated with said station leading to a distant exchange station, a second connecting line from said station leading to a local exchange station, a relay switching device associated with both of said connecting lines, having at least two operating windings, a switching element to be operated for initiating a call over said connecting line leading to said distant exchange forexciting only one winding of said relay for starting the execution of a connection with saiddistant connecting line and circuit connectionsrassociated with said subscriber station for rendering said relay inoperative upon initiating a call over said second con necting line leading to said local exchange by exciting both of said relay windings compensating each other. V '5. In combination in a telephone system, comprising a-subscriber station, a'first connecting line leading to a distant exchange station, a second connecting line leading to a local exchange station, means for enabling a call to be made overeither one of said connectlng llnes, said means including a relay associated with both of said connecting lines and circuit connections between said sub scriber station and said windingsoif said relay, whereby with the initiation of a call over said line to said distant exchange said relay is excited for operation and whereby with the initiation of a call over said connecting line leading to said local exchange said windingsof said relay are excited to compensate each other, 7 v

6. In combination in a telephone system, comprising a subscriber station,1a first connecting line associated with said station lead ing to a local automatic exchange, a relay associated with said first line operated with the initiation of a call to be madeover said first line, a circuit for said relay, a second connecting line from said station leading to a distant exchange station, a further relay associated with said circuit of saidfirst relay and means including a switching element and circuit connections, whereby said second relay is rendered inoperative with the initiation of a call over said first connecting line leading to said local exchange and whereby said 7 relay is rendered operative with the initiation of a call oversaid second connectingline leadi11 to sa-id'distantexchange. 1

g 1. In combinationin a telephone system, comprisinga subscriber station, a first con necting line associated with said station lead ing toa local exchange, a switching element operated with the initiation of a call'over said line, an automatic selector switch of said local exchange operated by said switching element, a controlling circuit of said switching element operated upon initiation of a call over said first connecting line leading to said local exchange, a second connect-ing line from said station leading to adistant exchange station, a call selector device associated with said second line for automatically selecting an idle line of a bunch of connectsaid second one'or said connecting lines com- I pensation of said relay windings is suppressed.

8. In combination in a telephone system, comprlsing subscrlber stat ons, an automatic exchange statlon for said subscriber stations,

including a selector. mechanism, connection lines between said subscriber stations and said selector mechanism, a relay device for each one of said connecting lines, means to operate said relay devices from said subscriber stations for initiating the operation of said selector mechanism for executing a connection with a desired called subscriber, a further automatic selecting apparatus including selector devices, connection lines from said subscriber statlons to sald. last selector de- 7 vices, a second relay device associated with all of said subscriber stations, means to operate said second relay from either one of said subscriber stations for initiating the operation of said last selector devlces for executing a connectlon over said second selector apparatus and means including circuit connections whereby said second relay is rendered inoperative when a call is made to said first exchange station.

9. In combination'in a telephone system, as 7 described in claim 8, a key to be closed for making a call over said second selector apparatus, at least two windings-of said second relay, an exciting circuit of said relay whereby one of said relay windings is short-circuited by the closing of said key and whereby both of said relay windings are excited when said key is in its open position to compensate each other.

In testimony whereof I affix my signature.

THE OD OR KORTHAUER. 

